1. Field of the Invention
The field of competitive protein binding assays or specific binding assays has greatly expanded, as its importance in the diagnostic field has become recognized. The ability to be able to detect a specific compound and measure the compound quantitatively has permitted the monitoring of the administration of a wide variety of drugs, the determination of an imbalance in a wide variety of hormones, the quantitation of physiologically active proteins, and the diagnosis of the presence of a pathogen. The different techniques have been distinguished in requiring or not requiring separation steps, the nature of the signal developed by the label, the development of the signal in a solution or on a surface and the manner of measurement for a quantitative determination.
In developing an assay, there are a number of considerations in devising the reagents and protocol. One consideration is the degree of sophistication of the individual performing the assay. There are many situations where it is desirable to have a relatively untrained individual be able to carry out an assay and obtain reasonably quantitative results. It is particularly desirable that the relatively untrained individual be able to carry out a quantitative assay in a simple, rapid test without the need for sophisticated equipment.
2. Description of the Prior Art
U.S. Pat. No. 4,168,146 describes an immunoassay employing immunochromatography with antigens followed by contacting the immunochromatograph with an aqueous solution containing labelled antibodies. U.S. Pat. No. 4,435,504 discloses a chromatographic immunoassay employing a specific binding pair member in a label conjugate which delineates a border whose distance from one end of the chromatograph relates to the amount of analyte present. An indicator strip useful in analytical chemical procedures is described in U.S. Pat. No. 3,715,192. U.S. Pat. No. 3,620,677 discloses an indicating device comprising in combination a porous capillary material and an impervious covering material enclosing at least a major portion of the exterior surfaces of the capillary material and disposed in intimate contact therewith defining an absorptive cavity of a preselected volume. A method for sonically securing articles in plastic mounts is described in U.S. Pat. No. 4,230,757. A contamination filter mask with a series of discreetly and scientifically oriented cutouts adapted to expose complementary regions of an adjacent filter for visual inspection and for particle count purposes is disclosed in U.S. Pat. No. 3,350,979. U.S. Pat. No. 2,371,405 describes a gas analysis apparatus.